A pellicle device is obtained by bonding a transparent optical thin film (pellicle film) to a pellicle frame having a shape corresponding to that of a photomask or a reticle, while expanding the film. The pellicle device prevents foreign materials from directly adhering onto the photomask or the reticle. In addition, even when the foreign materials adhere onto the pellicle film, such foreign materials do not form images on a semiconductor substrate or the like. Therefore, it is possible to accurately transfer a circuit pattern, and thus improve a manufacturing yield in a photolithography step.
In recent years, along with high integration of a semiconductor device or the like, a circuit pattern has been required to be drawn more finely with a smaller line width, and a mainstream exposure light source to be used in the photolithography step has employed a short-wavelength light. The light source employing such short-wavelength light has a high output power and high light energy. Therefore, when an inorganic acid, such as sulfuric acid, remains in an anodic oxide film on a surface of an aluminum frame material for forming the pellicle frame, there arises a problem in that such inorganic acid reacts with a basic substance, such as ammonia, which is present in an exposure atmosphere, to generate a reaction product, such as ammonium sulfate, and the reaction product causes fogging (haze) and affects a transferred image.
In view of the foregoing, there has been proposed a pellicle frame which is obtained by forming an anodic oxide film on the surface of an aluminum frame material through anodic oxidation treatment using an alkaline anodic oxidation solution containing, as an electrolyte, a salt of an organic acid, such as citric acid or tartaric acid, and thus reduced in the amount of the inorganic acid, such as sulfuric acid, and prevents the generation of haze as much as possible even under irradiation with high-energy light (see Patent Literatures 1 and 2).
Meanwhile, it is necessary to strictly control particles in a manufacturing process of the semiconductor device or the like, and also the pellicle device has generally been confirmed for the presence or absence of dust adhesion by visual observation or with an inspection device. However, in recent years, the thinning of the circuit pattern in the semiconductor device or the like has increasingly progressed, and along with this, inspection standards for the pellicle device have become stricter. Therefore, a white spot involving light reflection in visual inspection not only under irradiation with fluorescent light but also under irradiation with collected light, that is, a surface glittering defect of the pellicle frame (hereinafter sometimes referred to simply as “glittering” or the like) under irradiation with collected light is required to be reduced because such defect maybe falsely recognized as dust, or an incorrect pattern may be formed in the photolithography step when light from a light source is irregularly reflected owing to the glittering.